The MPLS WG Archive

[Kireeti Kompella <kireeti@juniper.net>]

Perhaps we've gone off on an tangent here.  The question
as I understood it is "when a *data* packet arrives at
the egress, can we know which ingress and which LSP it
travelled on?" -- and the answer is, not without some
extracurricular work.

Tan, can you clarify your question?

[I posted a reply to this earlier, but that seems to fallen
into a blackhole.]

Kireeti.

> 	In CR-LDP, the LSP-ID TLV consists of an IP
> address of the ingress LSR and a locally unique
> identifier.  Because it can be any address of the
> ingress LSR, it does not have to be an address the
> egress LSR will recognize (although it should be a
> "legal" address - i.e. not private or unregistered).
> 
> 	Therefore, I'm not sure how useful it is to 
> try to recapture information on the ingress LSR 
> using the LSP-ID TLV.
> 
> --
> Eric Gray
> 
> 
> > -----Original Message-----
> > From: Shahram Davari [mailto:Shahram_Davari@pmc-sierra.com]
> > Sent: Tuesday, May 30, 2000 7:27 AM
> > To: 'dwilder@baynetworks.com'; Tan Su Wei
> > Cc: mpls@UU.NET
> > Subject: RE: can egress know the ingress of a packet?
> > 
> > 
> > Hi,
> > 
> > I think in CR-LDP you may use LSP-ID TLV, which will give you 
> > the tunnel
> > ingress and the LSP ID. And in RSVP-TE you may use the Sender Template
> > Object, which will give you the same information. RRO may 
> > also be used in
> > RSVP-TE, however you only will get the ingress LSR 
> > information that you
> > need, but not which LSP it is coming from.
> > 
> > Regards,
> > -Shahram
> > 
> > >-----Original Message-----
> > >From: dwilder@baynetworks.com [mailto:dwilder@baynetworks.com]
> > >Sent: Tuesday, May 30, 2000 10:01 AM
> > >To: Tan Su Wei
> > >Cc: mpls@UU.NET
> > >Subject: Re: can egress know the ingress of a packet?
> > >
> > >
> > >Can we use the Record route Object for this?
> > >
> > >Dave
> > >
> > >> Dear all,
> > >> 
> > >>     I'd a doubt on :
> > >>         In a mpls network domain, for a particular 
> > >ingress-egress pair
> > >> with multiple LSPs in between them, is it possible when a 
> > >packet reach
> > >> the engress node, the engress node will know the following:
> > >>         i. ) the ingress node
> > >>         ii.) the lsp it travel
> > >> 
> > >>         Thanks for any reply.
> > >> 
> > >> Regards
> > >> Tan Su Wei